Identification and characterization of chromosomal relBE toxin-antitoxin locus in Streptomyces cattleya DSM46488.
Identification and characterization of chromosomal relBE toxin-antitoxin locus in Streptomyces cattleya DSM46488.
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卡特兰链霉菌 DSM46488 染色体 relBE 毒素-抗毒素位点的鉴定和表征
DOI：
10.1038/srep32047
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发表时间：
2016-08-18
影响因子：
4.6
通讯作者：
Ou HY
中科院分区：
文献类型：
--
作者：
Li P;Tai C;Deng Z;Gan J;Oggioni MR;Ou HY
II型毒素-抗毒素（TA）系统的relBE家族已在细菌中广泛报道，但在链霉菌中尚未报道。通过对链霉菌基因组TA对的保守结构域搜索，我们在catleya链霉菌（Streptomyces catleya）的染色体DSM 46488上发现了两个可能的相关位点relBE1sca和relBE2sca。过表达蓖麻毒素RelE2sca对大肠杆菌和lividans的生长有严重的抑制作用，但RelE1sca没有毒性作用。rel2sca的毒性可通过其同源物RelB2sca抗毒素的共表达而消除。此外，RelBE2sca复合物或抗毒素RelB2sca单独与RelBE2sca操纵子特异性相互作用并抑制其转录。在渗透胁迫下，relBE2sca操纵子转录与ClpP蛋白酶基因一起被诱导。随后的体内分析表明，抗毒素被ClpP降解。有趣的是，大肠杆菌抗毒素RelBeco能够减轻S. catleya rel2sca的毒性，而突变型RelB2sca（N61VM68L）却不能减轻E. coli RelEeco的毒性。relBEsca基因座的实验证明可能有助于研究II型TA系统在链霉菌生理和环境应激反应中的关键作用。
The relBE family of Type II toxin-antitoxin (TA) systems have been widely reported in bacteria but none in Streptomyces. With the conserved domain searches for TA pairs in the sequenced Streptomyces genomes, we identified two putative relBE loci, relBE1sca and relBE2sca, on the chromosome of Streptomyces cattleya DSM 46488. Overexpression of the S. cattleya toxin RelE2sca caused severe growth inhibition of E. coli and S. lividans, but RelE1sca had no toxic effect. The toxicity of RelE2sca could be abolished by the co-expression of its cognate RelB2sca antitoxin. Moreover, the RelBE2sca complex, or the antitoxin RelB2sca alone, specifically interacted with the relBE2sca operon and repressed its transcription. The relBE2sca operon transcription was induced under osmotic stress, along with the ClpP proteinase genes. The subsequent in vivo analysis showed that the antitoxin was degraded by ClpP. Interestingly, the E. coli antitoxin RelBeco was able to alleviate the toxicity of S. cattleya RelE2sca while the mutant RelB2sca(N61VM68L) but not the wild type could alleviate the toxicity of E. coli RelEeco as well. The experimental demonstration of the relBEsca locus might be helpful to investigate the key roles of type II TA systems in Streptomyces physiology and environmental stress responses.